Collaborative Research: Fast and efficient phase-change photonics using low-dimensional materials

该项目旨在展示一种同时利用相变材料和二维材料的独特性质的有源光学器件。有源光学设备目前是通过需要恒定电源的平台来实现的，这在具有零星调制的光学应用中是低能效的，例如基于光的数据存储。相变材料的可逆而稳定的光学响应已被探索作为解决这一问题的方法，因为它们的稳定状态允许零静态功率运行。这些特性及其纳米制造的多功能性导致了在从成像到片上光学计算的各种应用中前所未有的器件性能。然而，这种应用依赖于为近红外光谱(进行电信活动的地方)优化的相变材料。相比之下，其他几种经典和量子技术将受益于更接近可见光谱的调制。该项目旨在通过开发新型相变材料及其控制机制-微型加热器来填补这一空白，这些材料在可见光下是透明的，并与任何衬底兼容。为了制造微型加热器，该项目将探索二维材料的独特性质，如石墨烯，它是透明的，允许快速加热和冷却速度。该项目基于相变和二维材料的快速高效平台将广泛应用于超表面、光学滤光片、新型计算架构和可重构(量子)光子学等技术。本项目旨在探索使用由低维材料组成的微加热器作为一种高速、高效地控制用于硅以外平台的低损耗可重构相变光子器件的方法。Ge_2Sb_2Te_5、Sb_2Se_3等相变材料由于其折射率变化迅速、显著、非易失性和可逆性，在可重构光学器件中特别有应用前景。可重构的智能窗口、超表面和用于存储和计算的光子器件的实验演示重新点燃了人们对这些合金的兴趣。然而，探索对光学相变器件进行电气控制的工作仅限于波长1.2微米的光学不透明平台，与硅以外的光子平台不兼容，并且加热和冷却速度慢，限制了它们的开关速度和能源效率。因此，为了满足这些迫切的需求，本项目的目标是：1)开发新的解决方案，利用具有超快2D微加热器的基片无关平台来控制相变材料；2)通过开发新的相变合金并系统地研究其失效机理，提高光学透明度、速度和耐久性；3)展示高效可靠的波导集成。项目成果将直接关系到快速增长的非易失性光子学领域，包括自由空间应用，如超表面和光学滤光片，以及用于电信、神经形态计算和量子处理的光子集成电路。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project aims to demonstrate an active optical device that simultaneously exploits the unique properties of phase-change and two-dimensional materials. Active optical devices are currently achieved with platforms that require a constant power supply, which is energy inefficient in optical applications with sporadic modulation, such as light-based data storage. The reversible yet stable optical response of phase-change materials has been explored as a solution to this problem, given that their stable states allow for zero-static power operation. These properties and their nanofabrication versatility have resulted in unprecedented device performances in applications ranging from imaging to on-chip optical computing. However, such applications rely on phase-change materials optimized for the near-infrared spectrum (where telecommunications take place). In contrast, several other classical and quantum technologies would benefit from modulation closer to the visible spectrum. This project aims to fill this gap by developing novel phase-change material and their control mechanism, microheaters, that are transparent in the visible and compatible with any substrate. To create the microheater, this project will explore the unique properties of two-dimensional materials such as graphene, which is transparent and allows for fast heating and cooling speeds. This project’s fast and efficient platform based on phase-change and two-dimensional materials will be broadly applicable to technologies such as metasurfaces, optical filters, novel computing architectures, and reconfigurable (quantum) photonics. This project aims to explore the use of microheaters composed of low-dimensional materials as a method for high-speed and efficient control of low-loss reconfigurable phase-change photonic devices for platforms beyond silicon. Phase-change materials, such as Ge2Sb2Te5, Sb2Se3, etc., are particularly promising for reconfigurable optical devices owing to their fast, dramatic, non-volatile, and reversible change in refractive index. Experimental demonstrations of reconfigurable smart windows, metasurfaces, and photonic devices for memory and computing have reignited interest in these alloys. However, work exploring electrical control over optical phase-change devices has been limited to optically opaque platforms for wavelengths 1.2µm, not compatible with photonic platforms beyond silicon, and have slow heating and cooling rates which limit their switching speed and energy efficiency. Therefore, to fill these critical needs, this project aims to 1) develop new solutions for controlling phase-change materials using a substrate-agnostic platform with ultrafast 2D microheaters, 2) improve the optical transparency, speed, and endurance by developing new phase-change alloys and systematically studying their failure mechanisms, and 3) demonstrate efficient and reliable waveguide integration. The project outcomes will have immediate relevance in the fast-growing field of nonvolatile photonics, including free-space applications such as metasurfaces and optical filters and photonic integrated circuits for telecom, neuromorphic computing, and quantum processing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.